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linux/drivers/rtc/rtc-da9052.c
Steve Twiss 6406d96e74 rtc: da9053: fix access ordering error during RTC interrupt at system power on 
This fix alters the ordering of the IRQ and device registrations in the RTC
driver probe function. This change will apply to the RTC driver that supports
both DA9052 and DA9053 PMICs.

A problem could occur with the existing RTC driver if:

A system is started from a cold boot using the PMIC RTC IRQ to initiate a
power on operation. For instance, if an RTC alarm is used to start a
platform from power off.
The existing driver IRQ is requested before the device has been properly
registered.

i.e.
ret = da9052_request_irq()
comes before
rtc->rtc = devm_rtc_device_register();

In this case, an interrupt exists before the device has been registered and
the IRQ handler can be called immediately: this can happen be before the
memory for rtc->rtc has been allocated. The IRQ handler da9052_rtc_irq()
contains the function call:

rtc_update_irq(rtc->rtc, 1, RTC_IRQF | RTC_AF);

which in turn tries to access the unavailable rtc->rtc.

The fix is to reorder the functions inside the RTC probe. The IRQ is
requested after the RTC device resource has been registered so that
da9052_request_irq() is the last thing to happen.

Signed-off-by: Steve Twiss <stwiss.opensource@diasemi.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
2016-05-20 12:33:51 +02:00

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/*
* Real time clock driver for DA9052
*
* Copyright(c) 2012 Dialog Semiconductor Ltd.
*
* Author: Dajun Dajun Chen <dajun.chen@diasemi.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
*/
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/mfd/da9052/da9052.h>
#include <linux/mfd/da9052/reg.h>
#define rtc_err(rtc, fmt, ...) \
dev_err(rtc->da9052->dev, "%s: " fmt, __func__, ##__VA_ARGS__)
#define DA9052_GET_TIME_RETRIES 5
struct da9052_rtc {
struct rtc_device *rtc;
struct da9052 *da9052;
};
static int da9052_rtc_enable_alarm(struct da9052_rtc *rtc, bool enable)
{
int ret;
if (enable) {
ret = da9052_reg_update(rtc->da9052, DA9052_ALARM_Y_REG,
DA9052_ALARM_Y_ALARM_ON|DA9052_ALARM_Y_TICK_ON,
DA9052_ALARM_Y_ALARM_ON);
if (ret != 0)
rtc_err(rtc, "Failed to enable ALM: %d\n", ret);
} else {
ret = da9052_reg_update(rtc->da9052, DA9052_ALARM_Y_REG,
DA9052_ALARM_Y_ALARM_ON|DA9052_ALARM_Y_TICK_ON, 0);
if (ret != 0)
rtc_err(rtc, "Write error: %d\n", ret);
}
return ret;
}
static irqreturn_t da9052_rtc_irq(int irq, void *data)
{
struct da9052_rtc *rtc = data;
rtc_update_irq(rtc->rtc, 1, RTC_IRQF | RTC_AF);
return IRQ_HANDLED;
}
static int da9052_read_alarm(struct da9052_rtc *rtc, struct rtc_time *rtc_tm)
{
int ret;
uint8_t v[2][5];
int idx = 1;
int timeout = DA9052_GET_TIME_RETRIES;
ret = da9052_group_read(rtc->da9052, DA9052_ALARM_MI_REG, 5, &v[0][0]);
if (ret) {
rtc_err(rtc, "Failed to group read ALM: %d\n", ret);
return ret;
}
do {
ret = da9052_group_read(rtc->da9052,
DA9052_ALARM_MI_REG, 5, &v[idx][0]);
if (ret) {
rtc_err(rtc, "Failed to group read ALM: %d\n", ret);
return ret;
}
if (memcmp(&v[0][0], &v[1][0], 5) == 0) {
rtc_tm->tm_year = (v[0][4] & DA9052_RTC_YEAR) + 100;
rtc_tm->tm_mon = (v[0][3] & DA9052_RTC_MONTH) - 1;
rtc_tm->tm_mday = v[0][2] & DA9052_RTC_DAY;
rtc_tm->tm_hour = v[0][1] & DA9052_RTC_HOUR;
rtc_tm->tm_min = v[0][0] & DA9052_RTC_MIN;
ret = rtc_valid_tm(rtc_tm);
return ret;
}
idx = (1-idx);
msleep(20);
} while (timeout--);
rtc_err(rtc, "Timed out reading alarm time\n");
return -EIO;
}
static int da9052_set_alarm(struct da9052_rtc *rtc, struct rtc_time *rtc_tm)
{
struct da9052 *da9052 = rtc->da9052;
unsigned long alm_time;
int ret;
uint8_t v[3];
ret = rtc_tm_to_time(rtc_tm, &alm_time);
if (ret != 0)
return ret;
if (rtc_tm->tm_sec > 0) {
alm_time += 60 - rtc_tm->tm_sec;
rtc_time_to_tm(alm_time, rtc_tm);
}
BUG_ON(rtc_tm->tm_sec); /* it will cause repeated irqs if not zero */
rtc_tm->tm_year -= 100;
rtc_tm->tm_mon += 1;
ret = da9052_reg_update(da9052, DA9052_ALARM_MI_REG,
DA9052_RTC_MIN, rtc_tm->tm_min);
if (ret != 0) {
rtc_err(rtc, "Failed to write ALRM MIN: %d\n", ret);
return ret;
}
v[0] = rtc_tm->tm_hour;
v[1] = rtc_tm->tm_mday;
v[2] = rtc_tm->tm_mon;
ret = da9052_group_write(da9052, DA9052_ALARM_H_REG, 3, v);
if (ret < 0)
return ret;
ret = da9052_reg_update(da9052, DA9052_ALARM_Y_REG,
DA9052_RTC_YEAR, rtc_tm->tm_year);
if (ret != 0)
rtc_err(rtc, "Failed to write ALRM YEAR: %d\n", ret);
return ret;
}
static int da9052_rtc_get_alarm_status(struct da9052_rtc *rtc)
{
int ret;
ret = da9052_reg_read(rtc->da9052, DA9052_ALARM_Y_REG);
if (ret < 0) {
rtc_err(rtc, "Failed to read ALM: %d\n", ret);
return ret;
}
return !!(ret&DA9052_ALARM_Y_ALARM_ON);
}
static int da9052_rtc_read_time(struct device *dev, struct rtc_time *rtc_tm)
{
struct da9052_rtc *rtc = dev_get_drvdata(dev);
int ret;
uint8_t v[2][6];
int idx = 1;
int timeout = DA9052_GET_TIME_RETRIES;
ret = da9052_group_read(rtc->da9052, DA9052_COUNT_S_REG, 6, &v[0][0]);
if (ret) {
rtc_err(rtc, "Failed to read RTC time : %d\n", ret);
return ret;
}
do {
ret = da9052_group_read(rtc->da9052,
DA9052_COUNT_S_REG, 6, &v[idx][0]);
if (ret) {
rtc_err(rtc, "Failed to read RTC time : %d\n", ret);
return ret;
}
if (memcmp(&v[0][0], &v[1][0], 6) == 0) {
rtc_tm->tm_year = (v[0][5] & DA9052_RTC_YEAR) + 100;
rtc_tm->tm_mon = (v[0][4] & DA9052_RTC_MONTH) - 1;
rtc_tm->tm_mday = v[0][3] & DA9052_RTC_DAY;
rtc_tm->tm_hour = v[0][2] & DA9052_RTC_HOUR;
rtc_tm->tm_min = v[0][1] & DA9052_RTC_MIN;
rtc_tm->tm_sec = v[0][0] & DA9052_RTC_SEC;
ret = rtc_valid_tm(rtc_tm);
return ret;
}
idx = (1-idx);
msleep(20);
} while (timeout--);
rtc_err(rtc, "Timed out reading time\n");
return -EIO;
}
static int da9052_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct da9052_rtc *rtc;
uint8_t v[6];
int ret;
/* DA9052 only has 6 bits for year - to represent 2000-2063 */
if ((tm->tm_year < 100) || (tm->tm_year > 163))
return -EINVAL;
rtc = dev_get_drvdata(dev);
v[0] = tm->tm_sec;
v[1] = tm->tm_min;
v[2] = tm->tm_hour;
v[3] = tm->tm_mday;
v[4] = tm->tm_mon + 1;
v[5] = tm->tm_year - 100;
ret = da9052_group_write(rtc->da9052, DA9052_COUNT_S_REG, 6, v);
if (ret < 0)
rtc_err(rtc, "failed to set RTC time: %d\n", ret);
return ret;
}
static int da9052_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
int ret;
struct rtc_time *tm = &alrm->time;
struct da9052_rtc *rtc = dev_get_drvdata(dev);
ret = da9052_read_alarm(rtc, tm);
if (ret < 0) {
rtc_err(rtc, "failed to read RTC alarm: %d\n", ret);
return ret;
}
alrm->enabled = da9052_rtc_get_alarm_status(rtc);
return 0;
}
static int da9052_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
int ret;
struct rtc_time *tm = &alrm->time;
struct da9052_rtc *rtc = dev_get_drvdata(dev);
/* DA9052 only has 6 bits for year - to represent 2000-2063 */
if ((tm->tm_year < 100) || (tm->tm_year > 163))
return -EINVAL;
ret = da9052_rtc_enable_alarm(rtc, 0);
if (ret < 0)
return ret;
ret = da9052_set_alarm(rtc, tm);
if (ret < 0)
return ret;
ret = da9052_rtc_enable_alarm(rtc, 1);
return ret;
}
static int da9052_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct da9052_rtc *rtc = dev_get_drvdata(dev);
return da9052_rtc_enable_alarm(rtc, enabled);
}
static const struct rtc_class_ops da9052_rtc_ops = {
.read_time = da9052_rtc_read_time,
.set_time = da9052_rtc_set_time,
.read_alarm = da9052_rtc_read_alarm,
.set_alarm = da9052_rtc_set_alarm,
.alarm_irq_enable = da9052_rtc_alarm_irq_enable,
};
static int da9052_rtc_probe(struct platform_device *pdev)
{
struct da9052_rtc *rtc;
int ret;
rtc = devm_kzalloc(&pdev->dev, sizeof(struct da9052_rtc), GFP_KERNEL);
if (!rtc)
return -ENOMEM;
rtc->da9052 = dev_get_drvdata(pdev->dev.parent);
platform_set_drvdata(pdev, rtc);
ret = da9052_reg_write(rtc->da9052, DA9052_BBAT_CONT_REG, 0xFE);
if (ret < 0) {
rtc_err(rtc,
"Failed to setup RTC battery charging: %d\n", ret);
return ret;
}
ret = da9052_reg_update(rtc->da9052, DA9052_ALARM_Y_REG,
DA9052_ALARM_Y_TICK_ON, 0);
if (ret != 0)
rtc_err(rtc, "Failed to disable TICKS: %d\n", ret);
device_init_wakeup(&pdev->dev, true);
rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
&da9052_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc->rtc))
return PTR_ERR(rtc->rtc);
ret = da9052_request_irq(rtc->da9052, DA9052_IRQ_ALARM, "ALM",
da9052_rtc_irq, rtc);
if (ret != 0) {
rtc_err(rtc, "irq registration failed: %d\n", ret);
return ret;
}
return 0;
}
static struct platform_driver da9052_rtc_driver = {
.probe = da9052_rtc_probe,
.driver = {
.name = "da9052-rtc",
},
};
module_platform_driver(da9052_rtc_driver);
MODULE_AUTHOR("Anthony Olech <Anthony.Olech@diasemi.com>");
MODULE_DESCRIPTION("RTC driver for Dialog DA9052 PMIC");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:da9052-rtc");
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